Exogenous Glutathione Increases Arsenic Translocation Into Shoots and Alleviates Arsenic-Induced Oxidative Stress by Sustaining Ascorbate–Glutathione Homeostasis in Rice Seedlings

Abstract

Glutathione (GSH) plays diverse roles in the physiological processes, stress defense, growth, and development of plants. This study investigated the effects of exogenous GSH on the biochemical responses of reactive oxygen species and antioxidant levels in rice (Oryza sativa L. cv. Dasan) seedlings under arsenic (As) stress. As treatment inhibited growth; increased the level of superoxide, hydrogen peroxide, and malondialdehyde; and enhanced the uptake of As by the roots and shoots in hydroponically grown 14-day-old seedlings. Furthermore, it reduced GSH content and GSH redox ratios, which have been correlated with the decrease in ascorbate (AsA) redox state. Whereas the exogenous application of GSH in As-treated seedlings reduced As-induced oxidative stress, improved antioxidant defense systems by maintaining antioxidant and/or redox enzyme homeostasis, and increased the AsA and GSH contents, the GSH application also increased the As translocation from the roots to the shoots. These results indicated that the increase in GSH redox state can be linked to an increase in the AsA redox ratio via the induction of the AsA–GSH cycle. Therefore, the results suggest that exogenous GSH application should be a promising approach to enhance As stress resistance in rice plants.

Ascorbate-Mediated Modulation of Cadmium Stress Responses: Reactive Oxygen Species and Redox Status in Brassica napus

“…Plant antioxidant content and redox status are therefore informative for understanding plant tolerance to heavy metal stress. For example, it is known that the AsA, GSH, and NADPH levels and their redox ratios are the main factors influencing plant survival under various abiotic stress conditions (Mostofa et al, 2014;Jung et al, 2019). In our study, Cd-exposed plants did not exhibit changes in their NADPH levels, but their AsA and GSH levels significantly decreased in comparison to the untreated plants.…”

“…Cd toxicity negatively affects photosynthesis by reducing chlorophyll content, which adversely influences general plant growth and development by disrupting vital metabolic processes (Kim et al, 2008;Hong et al, 2013;Jan et al, 2015;Khan et al, 2015;Jung et al, 2016Jung et al, , 2017Jung et al, , 2018bFarooq et al, 2018). Recently, some studies have demonstrated that the exogenous application of sulfur (Khan et al, 2015;Jung et al, 2017;Tian et al, 2017), glutathione (Chen et al, 2010;Mostofa et al, 2014;Kim et al, 2017;Jung et al, 2019) or ascorbate (Chen et al, 2017;Jung et al, 2018a;Semida et al, 2018;Zhang et al, 2019) may alleviate different heavy metal stresses.…”

“…GSH is an antioxidant with a sulfhydryl group (-SH) that is important in scavenging the ROS produced by heavy metals (Srivastava et al, 2014;Singh et al, 2015;Kumar and Trivedi, 2018). Therefore, AsA and GSH directly play pivotal roles as antioxidants associated with scavenging ROS and regulating the critical components of the antioxidant defense system (Akram et al, 2017;Kim et al, 2017;Jung et al, 2018aJung et al, , 2019.…”

“…To accomplish this, five-leaf seedlings were grown in hydroponics treated with 10 µM Cd (CdCl 2 ) and were simultaneously sprayed with 250 mg kg −1 (1.42 mM) and 500 mg kg −1 (2.84 mM) AsA and 2 ml L −1 commercial surfactant (10% polyoxyethylene alkyl aryl ether and 20% sodium lignosulfonate). AsA was applied just once using a handheld sprayer delivering 1,000 L ha −1 of solution via flat-fan spray tips (Jung et al, 2019). Ten days after treatment, oilseed rape seedlings were removed from pots and tapped with a paper towel to remove water.…”

Arsenic Uptake and Accumulation Mechanisms in Rice Species

“…GSH disulphide is the oxidised form of GSH, which may be reprocessed to GSH by glutathione reductase via reduced nicotinamide adenine dinucleotide phosphate. Hence, these different components of the ascorbate-GSH cycle may have a vital character in protecting cells against oxidative damage resulted by As toxicity [75].…”